Pickerstick mounting and retracting devices



April 5, 1960 L. ca. URQUHART 2,931,395

PICKERSTICK MOUNTING AND RETRACTING' DEVICES Filed July 1. 1955 120%; G1. Ur W3,

United States Patent f PICERSTICK MOUNTING AND RETRACTING DEVICES Westboro, Mass, assignor to H. F. Mass, a corporation Lloyd G. Urquhart,

Liver-more Corporation, Allston, of Delaware The present invention relates to pickerstick controlling means of the type used for checking and retracting the pickerstick of a loom at the end of its inward or working stroke. More particularly, it relates to the devices for this purpose which form a part of the usual parallel motion, on which the pickerstick is mounted for rocking movement in such manner that the picker will travel parallel to the race plate.

conventionally, the pickerstick is retracted after each working stroke by a metallic spring which is used either to rotate a drum and wind thereonto the usual retracting strap attached to the foot of the pickerstick, or to pull directly on the retracting strap for the same purpose. Metallic springs of sufiicient power to retract the pickerstick properly have unavoidably had to have a substantial amount of residual tension even when the pickerstick had reached its extreme outward position. This is because metallic springs of the proper shape and character to work in the given locations in the loom necessarily had a relatively slow build-up of their tension owing to the small scope of movement of the parts impelled thereby. This meant that the pick motion had to overcome this initial resistance imposed by the spring on the pickersticks movement, in addition to the normal picking load of the inertia of the shuttle and pickerstick plus the usual friction. Furthermore, being necessarily pre-loaded initially, the spring and through it the strap were still urging the pickerstick outward as it approached its outward limit of motion. This added to the burden of the pickerstick check at both ends of the sticks stroke, because the stick alone in its recoil drove the check outward part way. This cut down the remaining outward travel of the pickerstick, normally saved for checking the shuttle yieldingly by having the stick await the impact a slight distance inward from the outer end of the slot made in the shuttle box for the pickerstick. Under these circumstances, the shuttle came to rest in varying positions, causing variations in the picking and sometimes inaccurate positioning of the shuttle during transfer. Further, the check had to be set tighter in order to stop the returning stick short of its outermost position, entailing needless wear on the check.

The major part of the power required to drive the loom is consumed in the picking of the shuttle. So any significant reduction that can be effected in the picking load is reflected in economy of power and hence in cost of operation.

To overcome these drawbacks of the prior pickerstick retractors, and to effect such economies, the invention lies in using a torsion spring element of rubber, preferably synthetic, or of other resilient plastic material capable of exerting a powerful effort in resuming its initial form when distorted therefrom through torsion. This torsion element is used to pull the usual retractor strap inwardly below the rocker, and thus to impel the pickerstick toward the outer end of its slot.

The peculiar feature of such a torsion spring is that when stressed upon the working stroke of the pickerstick Patented Apr. 5, 1960 iQQ its resistance builds up far more rapidly in proportion to its displacement than is practicable with a metallic spring. Hence when a thick bushing or cylinder of such resilient material is fixed on a stationary axial arbor and compressed radially and confined within a cylindrical shell around which the retractor strap is wrapped, the torque of the spring can be zero while the pickerstick waits part way inward from its outermost position, and yet build up to a degree where it possesses powerful resistance to the inward travel of the pickerstick as the latter approaches the end of its working stroke.

In the preferred embodiment of the form described, the resistance to the sticks movement inward builds up from zero to sufficient to stop the stick in about 15 of stick movement. The total angular movement of the stick is of the order of 18 to 20, as fixed by the slot in the shuttle box and the butters. So it is possible to leave about 3 to 5 of outward stick movement, beyond the point where the parts have recoiled to zero torque. Thereby an inch or so of pickerstick travel outward under impact of the shuttle, provided through the last-motion connection formed by the retractor strap, is saved for use in checking the shuttle.

Thus the invention device not only performs its primary function of retracting the pickerstick after each pick, but additionally imposes stifi resistance to inward movement of the stick in the last inch or two of such movement and also increases the scope of checking movement of the stick outward under impact of the shuttle. Hence it affords substantial help to the pickerstick check in checking the stick on its inward stroke and in arresting the stick and shuttle when the shuttle reenters the box.

An illustrative embodiment of the invention is shown in the accompanying drawings, in which:

Fig. l is a perspective view of the parts of the parallel motion and of the lower end of the pickerstick, with the retractor strap and the novel retractor of the invention.

Fig. 2 is an end view of the retractor or spring unit and its mounting stud.

Fig. 3 is a section on line 3-3 of Fig. 2.

Only so much of the pickerstick and its mounting is shown in the drawings as is needed for an understanding of the invention. The remainder of the picking motion preferably will be as conventionally employed but not illustrated here, comprising a pick cam on the loom camshaft displacing a pick ball mounted on a rockshaft having a stirrup attached to a lug strap surrounding the pickerstick 1 and jerking the latter forcibly inward to propel the shuttle through the shed.

The pickerstick 1 as usual extends through the rocker 3 to which it is fixed by bolt 5, and through a corresponding aperture in bracket 7 fixed by set screw 9 on lay rockshaft 11 extending through the loom side 13. Lug 15 on the bracket, and the bottom end portion of pickerstick 1, keep the rocker and bracket in alignment during the picking. The usual retractor strap 17 extends around the rounded outward end portion of the bottom of the stick 1, being fastened under washer 19 by bolt 5.

In accordance with the invention, the strap 17 is wrapped around and affixed by screw 23 to the cylindrical outside surface of a metallic shell 25 composed of two concentric cylindrical walls 27 and 29 united by a web 31 provided with openings 33. The outer wall 27 of this shell constitutes in effect a pulley surface around which the retractor strap is wrapped to varying degrees. Screw 23 is mounted in a tapped hole 24 therein.

Within the inner shell 29 is fixed the spring composed of a cylindrical body or thick bushing 35 of neoprene, rubber, or other suitable elastic material which has been mounted by means of its axial passage 37 upon a cylindrical stud 39 and then greatly compressed radially till it fits within the passage 41 in shell 29. The amount of compression of the torsion spring to be constituted by :the plastic element 35, in relation to its coefiicient of friction, is such that there cannot occur any slip or relative movement between the surfaces of the shell 25 and stud 39 and the surfaces of the bushing 35 which engage respectively with the interior of the shell and the stud, in the Working of the loom. Of course, to prevent slip, non-circular sections may be given the stud and the in side of shell 29 where heavy stresses are needed.

The stud 39 thus fixed within the elastic bushing 35 is fixed non-rotatably to bracket 7 on the lay rockshaft by putting its threaded tang 43 through a hole in a depending flange (not shown) at the back of bracket 7, with shoulder 45 on the stud against onesurface of the flange of the bracket and nut 47 and washer 49 tightened against the other side.

It will be seen that when the pickerstick is pulled toward the loom side 13 by the pick ball and lug strap (not shown) to throw the shuttle, the retractor strap 17 rotates the shell 25 around fixed stud 39, unwinding from the surface 27 thereof. This forces the exterior surface of the neoprene or other mass of resilient materialtq rotate along with shell 29 while the inner surface 37 is'held, from rotation by frictional engagement with the surface of stud 39, and in this way building up a power:

ful and oppositely directed torque within the elastic bus h ing'35.

This torque reacts reversely and strongly to wind the retractor strap 17 back onto the pulley surface 27, and thereby retracts the pickerstick 1 toward the outer end of its slot (not shown) in the shuttle box (not shown), as soon as the inward working stroke of the stick eornpelled by the pick cam and ball is completed.

The rate of build-up of the torque of the elastic spring member 35 is governed by the nature, consistency,

volume thickness, and related characteristics of the rubher or other elastic medium selected for the spring, and is so chosen that the device checks the stick with a re markably small overthrow as the pick ball reaches the high point of the cam. This saves the wear of the stick against its bumper. It also reduces wear and noise of the metallic parts by reducing overthrow of the pick ball and thus preventing violent return and resulting pounding of the pick ball against the cam. t v

The nature and design of the'spring thus constituted require no preloading and permit so rapid a build-up of the torque as to get the results described even though the torque returns to zero and the stick comes to rest some 3 to of .angular travel before it reaches the outward'end, of its scope. Hence an inch or so more of joint checking movement of check strap and stick which is usually wasted by the recording stick alone is-saved for use in checking the shuttle. Thereby the shuttle is brought yieldingly to rest without rebound and in correct position. The pickerstick can actually be positioned to await the shuttles impact at the same position at every pick, so as to box the shuttle identically at each pick.

This feature is of great value in obtaining uniform picky ing, and for accurate transfer of a full bobbin to the shuttle. Also, the excess picking power normally supplied to insure getting the shuttle home under varying conditions of the prior structures,'can be omitted.

The tension of the retractor spring is varied by turnstud.

ing the stud 39, while nut 47 is loosened for this purpose. Flats 51 are provided on the exposed end of'the stud for so doing, after which nut 47 is again retightened to maintain the adjusted angular position of the incomplete pick is of course eliminated. The same dimension of plastic spring 35 fits all looms of a given make and model, obviating the need to stock various sizes and strengths of retractor springs, or rightand lefthand patterns. The device never needs lubrication.

. While I have illustrated and described a certain form in which the invention maybe embodied, I am aware that manysmodificationsmay be made therein by any person skilled in the art, without departing from the scope of the invention as expressed in the claims. Therefore, I do not wish to be limited to the particular form shown, or to the. details of construction thereof, but

what I do claim is:

1 In a parallel motion for pickersticks, in combination, a lay rockshaft, a bracket fixed thereon, a rocker on the pickerstick rocking on the bracket, a torsion spring of resilient non-metallic material fixed on such bracket, and connecting means between the pickerstick and the torsion spring stressing the latter when the stick makes its working stroke and allowing the torque thus induced in the spring to drop tozero before the stick reaches the end of its reverse movement.

2. In a parallel motion for pickersticks, in combination, a bracket and a rocker thereon, a pickerstick fixed to the rocker, a cylindrical torsion spring of non-metallic resilient material operatively fixed on the bracket, and a retractor strap in connection with the stick and coiled around the torsion spring and twisting the latter about its surface of attachment to the bracket and thus stressing the spring during the working stroke of the stick, the spring recoiling and rewinding the strap and retracting the stick thereafter and expending its torque before the pickerstick resumes its starting position.

3. -A retractor spring for the parallel motion for the pickerstick-of a loom, having in combination a body of resilient non-metallic material, means on the parallel motion anchoring one surface of the material thereto, and means connecting another surface of the material to the pickerstick creating a-torque in the material only 1 after the pickerstick has moved '3 to 5 inwardly from its outermost position;

References Cited in the file of this patent UNITED STATES PATENTS 

